In case of memory devices used in a mobile era such as a mobile phone, a personal digital assistant (PDA) and so on, it is emerging as a major issue to save power consumed therein. Therefore, a dynamic random access memory (DRAM) used in the mobile era employs a power down mode in which internal power consumption is reduced to a lower one than a certain level in response to a signal inputted through a CKE pin.
FIG. 1 shows a block diagram of a semiconductor device with a conventional power down mode.
In the conventional power down mode using a CKE pin, internal circuits of the semiconductor device are designed not to receive any signals except a signal from the CKE pin when the signal is inputted through the CKE pin with a low state and, as a result, the semiconductor device can reduce its current consumption by controlling the operation of its internal circuits.
However, there is a problem of inducing a substantial amount of current consumption in the conventional semiconductor device in a state of the circuits being inactivated by off-leakage components that are generated as threshold voltages of MOS transistors constructing the semiconductor device are lowered, and static current components produced at analog circuits such as an internal voltage generator.